Mongolia is anticipating the return of dinosaur fossils smuggled out of the country after a ceremony officially transferred the remains from U.S. custody.

The dinosaur fossils were smuggled out of the Gobi desert but were recovered after agents from U.S. Immigration and Customs Enforcement discovered them. The bones were mislabeled. Eric Prokopi had intended to put the bones together when they reached American soil. Prokopi is a commercial paleontologist so assembling a Tyrannosaurus bataar skeleton was an easy task. The dinosaur skeleton had already been auctioned off for more than $1 million before U.S. Authorities intervened.

Prokopi cooperated with authorities in the recovery of the auctioned dinosaur bones, alerting them as well to many others that have not been discovered at the time. The British collector who was working with Prokopi handed over the rest to U.S. authorities. The paleontologist was sentenced to three months in jail. Prokopi would have faced a $250,000 fine and up to 17 years in prison if he did not cooperate.

U.S. Attorney Preet Bharara says there are more than 18 dinosaur fossils recovered and their return is a historic event for the U.S. Attorney's Office. These include a dinosaur egg, two Gallimimus skeletons, and two skeletons of Tyrannosaurus bataars. The whole set was said to be enough to stock a natural history museum.

James T. Hayes, the special agent heading the Homeland Security Investigations' New York Office, said that at least 31 dinosaur remains will be returned to Mongolian government eventually after determining that the fossils were poached illegally and smuggled out of Mongolia from 2005 to 2012.

The Tyrannosaurus bataar skeleton that have been previously auctioned was returned to Mongolian authorities more than a year before Thursday's ceremony. It was said to be 70 million years old. The skeleton is scheduled to be the first item to be displayed once the Central Dinosaur Museum being constructed by the Mongolian government is finished, said the country's minister of culture, sport and tourism.

"The people of Mongoli can now restore and display the relics as symbols of their status as a star within the paleontoligical firmament and astonishing symbols of Mongolian national pride," added Bharara.

The handing-over ceremony marks the culmination of the U.S. government's two-year effort at returning dinosaur fossils that have been smuggled into the country. Many were able to breach U.S. borders with false customs papers.